The invention relates to the field of porous
ceramic materials, and specifically relates to a dual-gradient pore-structure
sialon and
silicon carbide combined membrane tube and a preparation method thereof. The membrane tube material is composed of
sialon and
silicon carbide. The membrane tube has a dual-gradient filtering structure composed of a support body layer and a
surface membrane layer. The support body layer is composed of a combination of
sialon produced through a reaction and coarse
silicon carbide grains, and has an average pore size of 10-50mum. The
surface membrane layer is composed of a combination of sialon produced through a reaction and fine-particle
silicon carbide grains, and has an average pore size of 0.1-5mum. An overall
porosity of the membrane tube is within a range of 40-50%. The preparation method of the membrane tube sequentially comprises the steps of material preparation, support forming,
membrane layer preparation and firing. Isostatic pressing is adopted in the forming step, wherein a
forming pressure is controlled at 100-150MPa. The firing temperature is controlled at 1650-1850 DEG C, and a temperature maintaining time is 3-5h. The method is easy to realize. With the method, product performance can be ensured. The membrane tube provided by the invention has the advantages of high application temperature, high
acid corrosion resistance and high alkali
corrosion resistance. The membrane tube can be used in
filtration purification of various fluids with high temperature or low temperature, such as high-temperature high-press gas
filtration dedusting, water purification and the like.